The present invention relates to transmitting a charge to a device using inductive coils. Portable devices need a source of energy for operation. Generally, a rechargeable battery located within the device serves to power the device for a reasonable usage period and is then recharged during the evening or when the device is no longer in use. Users may effectively use these devices (i.e., phones, personal digital assistants, portable computers, diagnostic equipment) without running out of energy if the battery capacity is large enough and regularly charged in the battery charger.
Generally, a separate charger is provided with each portable device designed to meet the charging requirements of the battery and shape of the particular device. Unfortunately, the number of charging devices becomes unwieldy as the number of portable devices used by consumers and professionals continues to grow. Each charger requires a separate physical power source or wall-socket to supply the charge; wall-sockets are sometimes in limited supply in hotels, offices, or small apartments. Moreover, professionals traveling from home, to work, and to remote locations must also carry with them the appropriate chargers for each of the portable devices they use and rely upon.
Even if carrying these chargers were feasible, conventional chargers are sometimes problematic to use. Fixed wire cables or charging cradles used to charge some devices may lack sufficient mechanical and/or electrical contact with the device as the contacts on the cables or charging cradles wear out over time. This decrease in reliability of the charging device can negatively affect the user experience and also be costly for the manufacturer to repair and maintain through a warranty period.
Using fixed inductive couplings between the charger and the portable device addresses some but not all of the above failings. These chargers do not have mechanical or electrical contact with the device so are less prone to mechanical or electrical failures. They are also useful in situations where a conventional electrical contact would be dangerous in the particular environment (i.e., pacemakers embedded within the body or toothbrushes exposed to water during brushing). Nonetheless, even conventional inductive chargers require good positional matching between the shape of the charger and the device being charged. Consequently, portable devices charged inductively still require having multiple corresponding chargers uniquely designed for the particular battery being charged and device shape. These electrical, mechanical, and positional requirements for the inductive chargers may also restrict or compromise the design styling of the devices being charged.